planteen

69 ms·

661.
by planteen 10y ago
Yep. Think of it like right ascension, declination, and roll from astronomy. Given attitude, your position, and the time, you can know where you are pointing on the Earth (lat/lon).
662.
by planteen 10y ago
Star trackers are usually just used for attitude, not position. I've heard of research to use them in conjunction with a camera pointed at Earth to resolve coastlines to get position, but it's very theoretical at this point AFAIK.
663.
by planteen 10y ago
It's a LEON CPU (SPARC architecture) with a FPGA for hardware acceleration. Languages are C, MATLAB, and VHDL. The function is to take a picture of stars and return where you are pointed in inertial space with lots of accuracy.
664.
by planteen 10y ago
I worked on the software for the star trackers in these. Glad to hear they have already made contact. :-)
665.
by planteen 10y ago
Yeah I read it as tongue in cheek too.
666.
by planteen 10y ago
Don't heat pumps only work in temperate climates though? The low in Denver tomorrow is going to be 7 below...
667.
by planteen 10y ago
Yep. Many forms of petroleum are also very convenient for energy storage. So even an EROI less than 1 they would still have utility. 1 L of diesel has about 39 MJ of energy. That's about 10 kWH (a Tesla Powerwall) in the size of a Nalg
668.
by planteen 10y ago
Not to mention what the clock source is. PLLs (internal or external) can become unlocked. RC oscillators have a lot of temperature dependence.
669.
by planteen 10y ago
> Shouldn't eminent domain be illegal when the land is going to a private company and not public use? The constitution is kind of clear on that, not sure how they get around it There was a controversial 5-4 Supreme Court decision on
670.
by planteen 10y ago
I'd be interested more about the steering (attitude control). Where did you find that? I don't see it in the article. It seems like the dominant force here is going to be the radiation pressure of the laser hitting it, at least in
671.
by planteen 10y ago
Not to mention it wouldn't be able to point at the star without some actuators.
672.
by planteen 10y ago
RHEL is comparable to running LTS Ubuntu. If you want bleeding edge latest, that's what Fedora is for, not RHEL.
673.
by planteen 10y ago
NVM, deleted
674.
by planteen 10y ago
I don't think that is it. The tools aren't open source free, but they are dollar free. Xilinx is the leader in FPGAs and their tools are free. Lattice tools are also free. Not sure about Altera, who is #2. I've worked multipl
675.
by planteen 10y ago
Here's a whitepaper from Seagate with some details: http://www.seagate.com/files/www-content/product-content/ent... Sounds like they design them for a 5 year life.
676.
by planteen 10y ago
So that means C looks pretty safe... 44 years. C++ is 33 years.
677.
by planteen 10y ago
When you look at the SVG spec, it is quite simple, and not very different from what you would have to do in graphics APIs like OpenVG anyway for the operations you have described.
678.
by planteen 10y ago
I had a nasty bug like that once as well. It was in some FPGA logic written in VHDL with an overflow on a FIR filter. Recreating the problem was very difficult since it only happened near max signal power with a noisy input. The correct sol
679.
by planteen 10y ago
> The fact that the overhead is only 2x for a tight inner loop should be a cause for celebration, not dire warnings. And as the author himself shows, it's very easy to disable overflow checking on a per-operation basis when you want
680.
by planteen 10y ago
Here's another example like your Windows rollover - timing rollover caused the loss of the Deep Impact spacecraft. "On September 20, 2013, NASA abandoned further attempts to contact the craft.[76] According to A'Hearn,[77] th
681.
by planteen 10y ago
SVG is just XML, so any language that can write XML can handle SVG. There are plenty of tools to rasterize the SVG to a PNG. I don't think the choice of language matters very much.
682.
by planteen 10y ago
AES and Reed-Solomon codes
683.
by planteen 10y ago
Two applications off the top of my head: Reed-Solomon encoding and bigint math.
684.
by planteen 10y ago
Nothing beats the village of Ytterby in Sweden... 4 elements named for it! yttrium (Y) erbium (Er) terbium (Tb) ytterbium (Yb) https://en.wikipedia.org/wiki/Ytterby
685.
by planteen 10y ago
I rented an Iridium sat phone while on a month long caving expedition in a remote part of Peru. It was nice to have in case of emergencies and also to check in daily to let family back home know we were ok.
686.
by planteen 10y ago
Agreed, I don't see why this is front page material.
687.
by planteen 10y ago
Bit fields certainly have lots of uses that can't be replaced by databases.
688.
by planteen 10y ago
Honestly I hope so. Good riddance. SPARC is strange compared to other RISC architectures. I was never a fan of the register windows (and associated overflows) and the global/out/local/in register types. Reading the ASM was na
689.
by planteen 10y ago
Electronics from the 50s and 60s still can be used. You need to be gentle when powering them on to ensure the capacitors haven't reversed. My trick is to use a light bulb in series to the AC input to drop the voltage. As long as there
690.
by planteen 10y ago
Nonsense, Kalman filters are well understood and widely used in spacecraft attitude dynamics and control systems. In fact, I'd argue that a Kalman filter is industry standard for that work. It's typical on teams doing GNC (guidanc

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